Polycarbonates are synthetic thermoplastic resins that can, for example, be derived from bisphenols and phosgene, or their derivatives. Polycarbonates are a useful class of polymers having many desired properties. They are useful for forming a wide variety of products, such as by molding, extrusion, and thermoforming processes. Such products include articles and components that include auto parts, electronic appliances and cell phone components. Because of their broad use, particularly in electronic applications or visually oriented applications, such as light covers, see-through protective coverings, lenses, and transparent films, it is desirable to provide polycarbonates with improved flame resistance and impact strength while other attractive properties are retained. In particular, it is highly desired to provide polycarbonates that can exhibit improved flame resistance and impact strength for thin samples without requiring the use of halogenated flame retardant additives.
Non-halogenated flame retardants have been incorporated into polycarbonate resins for this purpose. Exemplary flame retardant agents include phosphorous acid esters, various silicate fillers and certain salts. It has been difficult, however, to meet the strictest standard of flame retardancy in thin samples with foregoing flame retardants as these flame retardant agents generally adversely affect the desirable physical properties of polycarbonate compositions, particularly in impact strength and/or heat resistance.
Thus, there remains a continuing need in the art for polycarbonate compositions that can readily produce articles with a balance of high impact strength, increased flame retardance for relatively thin samples achieved without the use of halogenated flame retardant agents.